1. Field of the Invention
This invention relates to the production of chlorine and caustic employing mercury amalgam cells and, more particularly, to the prevention of mercury contamination by plant effluent streams to the environment and to the recovery of mercury from said streams. This process is particularly adaptable to the use of a poor grade of sodium chloride, namely, one which assays from about 95-98 percent sodium chloride.
2. Description of the Prior Art
The mercury amalgam electrolytic cell for the production of chlorine and caustic has been used primarily because of the high grade caustic soda which is produced. However, the loss of mercury from the effluent streams issuing from these electrolytic cells creates serious ecological problems. Furthermore, the loss of mercury is a costly expenditure in the caustic and chlorine producing plants. Accordingly, it is imperative that means are found for the removal and recovery of mercury and/or other heavy metal ions from both solid and liquid plant effluents.
U.S. Pat. No. 3,788,842 teaches the treatment of a stream containing mercury with steel turnings. U.S. Pat. No. 3,836,442 employs a sulfide process for the extraction of mercury from solid wastes. U.S. Pat. No. 3,755,110 and 3,691,037 teach the treatment of mercury sludge with sodium hypochlorite. None of the patents teach the totality of the invention as claimed in this application which treats both solid and liquid waste in one process.